A: There are a bushel of reasons why organic food costs more than conventional food. Some of them:

-- Organic produce, meat and dairy simply cost more to produce than their conventional counterparts.

Limits on pesticides, for instance, mean more hand-weeding. They also mean farmers run a higher risk of losing all or part of a year's crop.

"There aren't as many tools in the toolbox to deal with pest outbreaks or diseases," said Nancy Creamer, director of the Center for Environmental Farming Systems at North Carolina State University.

Some of the things organic farmers can't use that conventional farmers can: Sewage sludge, which is cheap to buy, and chemical fertilizers, which are both cheap to buy and cheap to transport. Instead, organic farmers fertilize their land with compost and animal manure, which is bulkier and more expensive to ship, Creamer said.

While conventional farmers can use every acre to grow the crops that fetch the highest prices, organic farmers use crop rotation to keep their soil healthy. Instead of planting a cash crop on every acre every year, they rotate fields and plant "cover crops" that are plowed to improve the soil's nutrients for the long term.

"When you're rotating crops, you're not necessarily growing all your highest value crops all the time, which is different than a conventional system," said Catherine Greene, an agricultural economist at the USDA.

Organic feed for cattle and other livestock can cost twice as much as conventional feed, said George Siemon, CEO of the Organic Valley co-op, the largest organic farmers' co-op in the country. A ton of organic cattle feed can cost from $350 to $400 a ton versus $220 or less for a ton of conventional feed, he said.

-- The demand for organic food is greater than the supply, Greene said. But she added "we don't have enough data to tease out how much (of the price difference) is due to higher-cost production versus the imbalance between supply and demand."

-- Some of the cost difference comes from retailers, Siemon said, since some organic products don't sell as quickly as their conventional counterparts. "The retailer wants to make the same amount of money, per space," he said.

Finally, organic farming proponents say conventionally grown food includes invisible costs, including a higher incidence of some cancers and other diseases in farm workers and their children and contamination of water supplies.

They argue that large corporate farms can make money on high volume and low prices, but those low prices have pushed millions of family farms into bankruptcy.

Four million farmers have disappeared in the last 40 years, Siemon said.

"Farmers have seen organics as a glimmer of hope for their economic survival," he said. "They're trying to overcome bankruptcy pricing."

One tenant of organic farming is sustainability, he said. "Shouldn't that also be about economic sustainability?"

Chef Alice Waters, a champion of locally grown and organic foods, justified one farm's $3 organic peaches to The New York Times.

"Maybe they'll make $5,000 more a year," she said. "Well, hooray. We're not making millionaires here. We're supporting sustainable agriculture."